This invention is directed to the providing of a suitable auxiliary or storm window structuure which is utilized in combination with a conventional window sash. Many types of structures have been heretofore developed for that purpose with the most common and oldest type being a rigid frame provided with one or more panes of glass. A storm window of that construction is generally adapted to being mounted exteriorally of the primary window sash and it is this mounting which presents substantial problems that prevent its widespread continued utilization. The first and obvious problem is that such a window can only be safely installed from the exterior of the building structure. This is readily accomplished in one or two story dwellings but is an unacceptible type of mounting for the high-rise, multiple story buildings where such mountings would require the use of scaffolding or other exterior support means for the workers. A second major disadvantage to the use of such storm windows in multi-story buildings is that most building code regulations concerning such structures require that the windows be capable of being readily opened from the interior of the associated room. This is a very important feature with respect to public buildings such as hotels where a quick means of emergency egress is essential. Also, the ability to open a window to obtain ventilation is particularly advantageous.
Another important type of window, or window which can provide the same advantages of the double hung sash type, is a twin panel glass variously designated as a thermal pane window. While these dual panel structures do provide an acceptable degree of thermal insulation as to the glass itself, these structures are totally dependent on the ability of a supporting frame to maintain an adequate weather seal with respect to the mounting frame. Where commercial buildings incorporate metal frames for such windows, this is difficult to achieve without extensive and repeated caulking and sealing efforts. Also, this type of window is particularly expensive.
A third and newer technique attempting to provide a suitable auxiliary or storm window is the use of thin sheets of plastic materials, either rigid or flexible, that are relatively inexpensive. The flexible plastic sheets are generally designed to be secured to the window frame by frame elements that are often not structurally self-supporting to maintain the low cost. While this type of mounting can be achieved, these windows require substantial time for installing. The rigid sheets also are difficult to install and require a substantial amount of time for installation. Furthermore, these windows which may be mounted either interiorally or exteriorally of the conventional sash, often can only be mounted in a relatively permanent manner. They are not adapted to be readily removed without use of tools such as screw drivers and other similar implements and removal procedures often result in a high percentage of breakage. Consequently, auxiliary or storm windows of this construction are totally unacceptable in commercial buildings and residence structures such as hotels, where the residents must be enabled to quickly remove or open the windows for ventilation or emergency egress in the event of fire.